Isolation of cellulose-II nanospheres from flax stems and their physical and morphological properties

In this study, cellulose-II nanospheres (CNS) were extracted from flax fibers and analyzed to understand the crystalline, functional and morphological properties by means of X-ray Diffraction (X-RD), Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopy (SEM). FT-IR and SEM results indicate the effective removal of extractives, lignin and hemicellulose. X-RD results clearly show the transformation from cellulose-I to cellulose-II during the mercerization process. Further, the resulting cellulose fibers were treated with sulfuric acid in order to obtain cellulose nanospheres (CNS). The morphology was measured by SEM, Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM). The size distribution and the surface charge of CNS were investigated by Small-Angle X-ray Scattering (SAXS) and Nanosizer. The results indicate a size distribution of CNS between 20 and 90 nm moderately dispersed. Finally, the transversal elastic modulus of CNS-II was determined by using AFM, and results reveal the range varying from 6 to 25 GPa.